Volume 3: The Swiss Years: Writings 1909-1911
Page547(585 of 682)

DOC. 26 THE PROBLEM OF SPECIFIC HEATS 547 effect as well as of various alternative explanations of the photoelectric effect, see Stuewer 1970, Wheaton 1978, and Vol. 2, the editorial note, "Einstein's Early Work on the Quantum Hypothe- sis," pp. 141-142. [38]Comparison with the German typescript indicates that the word "ereignissweise" ("in single events") has been deleted between the words "Energie" and "in großen Quanten." As documented by his correspondence, Einstein took an active interest in the contemporary exper- imental research on radiation fluctuations. [39]Evidence for the anisotropic distribution of the energy of y-rays was offered by Edgar Meyer's experiments; see Meyer, E. 1910, §4. [40]The fact that only a small fraction of the electrons reach the maximal energy was estab- lished for the photoelectric effect by Lenard (see Lenard 1902) and stressed by Einstein in Einstein to Johannes Stark, 7 December 1907. For Einstein's use of the high energy of second- ary electrons as an argument against Sommerfeld's classical treatment of X rays, see Einstein to Arnold Sommerfeld, 19 January 1910. [41] Einstein had earlier posed this question to August Hagenbach, an experimental physicist at the University of Basel, who confirmed the classical view that absorption concerns only the amplitude of radiation; see Einstein to August Hagenbach, 6 July 1908, and August Hagenbach to Einstein, 9 July 1908. The same question also appears in Einstein's Scratch Notebook (Appendix A), [p. 22]. Planck as well as Lorentz referred to interference phenomena as a key argument against the existence of light quanta; see the comment by Planck in Einstein et al. 1909c (Vol. 2, Doc. 61) and H. A. Lorentz to Einstein, 6 May 1909. In 1910 Einstein had apparently asked Pierre Weiss to perform an interference experiment to test this question, but he lost interest in it, "because I no longer believe in localized light quanta (at present)" ("weil ich an die räumlichen Lichtquanten nicht mehr glaube (gegenwärtig)"); see Einstein to Jakob Laub, 4 November 1910. For a historical account of experiments related to the problem of interference, see Wheaton 1983, pp. 140-147. [42]Einstein had discussed experiments on the absorption of X-rays involving thin layers with Jakob Laub; see Einstein to Jakob Laub, 30 July 1908. For earlier comments by Einstein on the problem of time delay in absorption processes in connection with Sommerfeld's theory, see Einstein to Michele Besso, 11 September 1911, and Sommerfeld et al. 1911 (Doc. 24). For a discussion of contemporary measurements of delay times, see Wheaton 1983, pp. 187-188. [43]For the relationship between temperature, frequency, and intensity of radiation, see Planck 1906, §100, and, in particular, eq. (136). In their correspondence, Einstein and Lorentz had earlier discussed the possible dependency of the energy of secondary electrons on the temperature of the radiation; see H. A. Lorentz to Einstein, 6 May 1909, and Einstein to H. A. Lorentz, 23 May 1909. [44]Sommerfeld 1911a; see also Sommerfeld's lecture at the Solvay Congress, Sommerfeld 1914. [45]See Nernst 1911c and note 26 above. [46]For a more explicit discussion by Einstein of Sommerfeld's hypothesis, see his remarks on Sommerfeld's Solvay lecture in Doc. 25, pp. 514-518. [47]The text starting with "Nernst und Lindemann haben bereits" through "In derartigen Fällen könnte man" replaced the following in the German typescript: "Es scheint nicht, dass diese Formeln eine brauchbare Annäherung ergeben; meiner Rechnung nach müsste nämlich nach ihnen die spezifische Wärme cp des Wasserstoffs schon bei gewöhnlicher Temperatur um mehrere etwa 4% kleiner sein als der gastheoretische Wert; was die Erfahrung nicht bestätigt. Es mag daran vielleicht die vereinfachende Annahme schuld sein, dass alle Moleküle gleich rasch rotieren. Nernst hat, wenn ich nicht irre, schon darauf hingewiesen, dass die Unter- suchung der ultraroten Absorption solcher zweiatomigen Gase, welche vermutlich ein elek- trisches Moment besitzen (z.B. HCl) von grossem Interesse wäre. In der That könnte man" ("It does not seem that these formulas provide a useful approximation; in fact, according to my calculation, on the basis of these [formulas] the specific heat cp of hydrogen would have to be less than the value from the theory of gases by some 4% or more already at ordinary tempera- tures, which is not confirmed by experiment. This might be due to the simplifying assumption